Metathesis reaction from bio-based resources: Synthesis of diols and macrodiols using fatty alcohols, β-citronellol and natural rubber

Diols and macrodiols (hydroxytelechelic compounds) were synthesized via metathesis from fatty alcohols and terpenes derivatives using [(1,3-bis-(2,4,6-trimethylphenyl)-2-imidazolidinylidene) dichloro (o-isopropoxyphenylmethylene) ruthenium] (second generation Hoveyda-Grubbs catalyst) as catalyst. The unsaturated diols: octadec-9-ene-1,18-diol, icos-10-ene-1,20-diol and 3,10-dimethyl-dodec-6-ene-1,12-diol were obtained with yields of 45–98% using mild conditions reaction, in absence of solvent. In other hand, macrodiols with high yields (>97%) and Fn ≈ 2 were synthetized in one-pot reaction by cross-metathesis degradation from the natural rubber (NR) and the cis-1,4-polybutadiene (PB), using the unprotected free alcohols, 9-decen-1-ol (9de), 10-undecen-1-ol (10un) and β-citronellol (βc), as chain transfer agents (CTA's). The results suggest that 9de, 10un and βc were effective CTA's in such metathesis reactions. The molecular weights were changed in a wide range (297 g/mol to 13,650 g/mol) controlling the rubber/CTA ratio and were in good agreement with their theoretical values.